Browsing by Author "Chan, Manwei"

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    Four-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: On-sky Receiver Performance at 40, 90, 150, and 220 GHz Frequency Bands
    (2022) Dahal, Sumit; Appel, John W.; Datta, Rahul; Brewer, Michael K.; Ali, Aamir; Bennett, Charles L.; Bustos, Ricardo; Chan, Manwei; Chuss, David T.; Cleary, Joseph; Couto, Jullianna D.; Denis, Kevin L.; Dunner, Rolando; Eimer, Joseph; Espinoza, Francisco; Essinger-Hileman, Thomas; Golec, Joseph E.; Harrington, Kathleen; Helson, Kyle; Iuliano, Jeffrey; Karakla, John; Li, Yunyang; Marriage, Tobias A.; McMahon, Jeffrey J.; Miller, Nathan J.; Novack, Sasha; Nunez, Carolina; Osumi, Keisuke; Padilla, Ivan L.; Palma, Gonzalo A.; Parker, Lucas; Petroff, Matthew A.; Reeves, Rodrigo; Rhoades, Gary; Rostem, Karwan; Valle, Deniz A. N.; Watts, Duncan J.; Weiland, Janet L.; Wollack, Edward J.; Xu, Zhilei
    The Cosmology Large Angular Scale Surveyor (CLASS) observes the polarized cosmic microwave background (CMB) over the angular scales of 1 degrees less than or similar to theta <= 90 degrees with the aim of characterizing primordial gravitational waves and cosmic reionization. We report on the on-sky performance of the CLASS Q-band (40 GHz), W-band (90 GHz), and dichroic G-band (150/220 GHz) receivers that have been operational at the CLASS site in the Atacama desert since 2016 June, 2018 May, and 2019 September, respectively. We show that the noise-equivalent power measured by the detectors matches the expected noise model based on on-sky optical loading and lab-measured detector parameters. Using Moon, Venus, and Jupiter observations, we obtain power to antenna temperature calibrations and optical efficiencies for the telescopes. From the CMB survey data, we compute instantaneous array noise-equivalent-temperature sensitivities of 22, 19, 23, and 71 mu K-cmp root s for the 40, 90, 150, and 220 GHz frequency bands, respectively. These noise temperatures refer to white noise amplitudes, which contribute to sky maps at all angular scales. Future papers will assess additional noise sources impacting larger angular scales.
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    Two Year Cosmology Large Angular Scale Surveyor (CLASS) Observations: Long Timescale Stability Achieved with a Front-end Variable-delay Polarization Modulator at 40 GHz
    (2021) Harrington, Kathleen; Datta, Rahul; Osumi, Keisuke; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Brewer, Michael K.; Bustos, Ricardo; Chan, Manwei; Chuss, David T.; Cleary, Joseph; Couto, Jullianna Denes; Dahal, Sumit; Dunner, Rolando; Eimer, Joseph R.; Essinger-Hileman, Thomas; Hubmayr, Johannes; Espinoza Inostroza, Francisco Raul; Iuliano, Jeffrey; Karakla, John; Li, Yunyang; Marriage, Tobias A.; Miller, Nathan J.; Nunez, Carolina; Padilla, Ivan L.; Parker, Lucas; Petroff, Matthew A.; Pradenas Marquez, Bastian; Reeves, Rodrigo; Fluxa Rojas, Pedro; Rostem, Karwan; Valle, Deniz Augusto Nunes; Watts, Duncan J.; Weiland, Janet L.; Wollack, Edward J.; Xu, Zhilei
    The Cosmology Large Angular Scale Surveyor (CLASS) is a four-telescope array observing the largest angular scales (2 less than or similar to l less than or similar to 200) of the cosmic microwave background (CMB) polarization. These scales encode information about reionization and inflation during the early universe. The instrument stability necessary to observe these angular scales from the ground is achieved through the use of a variable-delay polarization modulator as the first optical element in each of the CLASS telescopes. Here, we develop a demodulation scheme used to extract the polarization timestreams from the CLASS data and apply this method to selected data from the first 2 yr of observations by the 40GHz CLASS telescope. These timestreams are used to measure the 1/f noise and temperature-to-polarization (T -> P) leakage present in the CLASS data. We find a median knee frequency for the pair-differenced demodulated linear polarization of 15.12 mHz and a T -> P leakage of <3.8 x 10(-4) (95% confidence) across the focal plane. We examine the sources of 1/f noise present in the data and find the component of 1/f due to atmospheric precipitable water vapor (PWV) has an amplitude of 203 +/- 12 mu K-RJ root s for 1 mm of PWV when evaluated at 10 mHz; accounting for similar to 17% of the 1/f noise in the central pixels of the focal plane. The low levels of T -> P leakage and 1/f noise achieved through the use of a front-end polarization modulator are requirements for observing of the largest angular scales of the CMB polarization by the CLASS telescopes.